Species | Alsatites cycloides WÄHNER |
Author | WÄHNER |
Group | Alsatiten/Alpinoceraten |
Horizon | pachygaster-horizon |
Zone | marmoreum-zone |
Stage | Upper Hettangian |
Description
The wide-necked species has a highly oval WQ, flattened flanks and a roof-shaped sharpened outer side. Furrows may be indicated next to the "keel" thus formed.
The ribs start slightly retroradiate at the suture, run rather straight and proradiate over the flanks and then bend forward near the external side where they first almost disappear and can then be observed again on the keel. This sculpture of the keel may disappear with age.
* Description according to Wähner (1886), supplemented
Compare
Characteristic for this species is the sharpening of the external side, whereby there are no furrows and thus no set-off keel. Even Alsatites proaries has more distinct furrows next to the keel when old.
A. cycloides differs from the very similar A. doetzkirchneri by the larger umbilical width and straighter, less numerous ribs. The WQ in A. doetzkirchneri is much higher than wide.
Dimension
Dimensions at D= 87mm (according to Wähner):
Nw % v. D: ca. 64%
Wh % v. D: ca. 20%
Wb % v. D: ca. 14%
Literature
- 1886 Arietites cycloides n.f. – Wähner S. 142, Taf, 23.1
- 2000 Alsatites cycloides Wähner – Kment S. 203